The automatic tranny on my 90 4Runner shifts pretty roughly before it gets warm. Definitely enough for other people to comment.

If I keep the RPM's down low (and drive slow) so it doesn't shift for the first 5 minutes or so, it's fine.

But if I jump in a drive away, it'll shift pretty hard for at ten minutes of driving.

I checked the fluid level, it seems fine, if anything it's a little high. This is also a rebuilt tranny (right before I got it supposedly) but I have no idea how many miles are on it.

What could be causing this? Also, it just started doing this a few weeks ago.

 

My 89 runner is doing the same. I just had a rebuild motor put in and now the problem.

 

The cable that goes from the throttle body to the tranny controls line pressure.

It might need adjusting.

Auto trannys like the correct amount of fluid.
Check idling in neutral with tranny warm to hot.